Add trace event for detecting main frame in loading metrics.

third_party/WebKit/Source/web/WebLocalFrameImpl.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 2394 matching lines @@
   return frame()
       ->frameScheduler()
       ->unthrottledTaskRunner()
       ->toSingleThreadTaskRunner();
 }
 
 WebInputMethodControllerImpl* WebLocalFrameImpl::inputMethodController() const {
   return m_inputMethodController.get();
 }
 
+void* WebLocalFrameImpl::frameIdForTracing() const {
+  return frame();
+}
+
 void WebLocalFrameImpl::extractSmartClipData(WebRect rectInViewport,
                                              WebString& clipText,
                                              WebString& clipHtml) {
   SmartClipData clipData = SmartClip(frame()).dataForRect(rectInViewport);
   clipText = clipData.clipData();
 
   WebPoint startPoint(rectInViewport.x, rectInViewport.y);
   WebPoint endPoint(rectInViewport.x + rectInViewport.width,
                     rectInViewport.y + rectInViewport.height);
   VisiblePosition startVisiblePosition =
@@ skipping 13 matching lines @@
         createMarkup(startPosition, endPosition, AnnotateForInterchange,
                      ConvertBlocksToInlines::NotConvert, ResolveNonLocalURLs);
   } else {
     clipHtml =
         createMarkup(endPosition, startPosition, AnnotateForInterchange,
                      ConvertBlocksToInlines::NotConvert, ResolveNonLocalURLs);
   }
 }
 
 }  // namespace blink